Design the network for a new 200-person office

The interviewer says: "We are opening an office for 200 people next spring. Design the network." You have a whiteboard and about 30 minutes. The company already runs a head office, uses Microsoft 365 and a SaaS CRM, and gives every site its own /16 out of 10.0.0.0/8. This office gets 10.20.0.0/16.